import java.util.ArrayList;
import java.util.List;

// https://leetcode.cn/problems/count-of-smaller-numbers-after-self/submissions/679547317/
public class test3 {
    int[] ret;
    int[] index;// 标记下标
    int[] tmpIndex;
    int[] tmpNums;
    public List<Integer> countSmaller(int[] nums) {
        int n=nums.length;
        ret=new int[n];
        index=new int[n];
        tmpIndex=new int[n];
        tmpNums=new int[n];
        for(int i=0;i<n;i++) {
            index[i]=i;
        }
        mergeSort(nums,0,n-1);
        List<Integer> l=new ArrayList<>();
        for(int x:ret) {
            l.add(x);
        }
        return l;
    }
    public void mergeSort(int[] nums,int left,int right) {
        if(left>=right) return;
        int mid=(left+right)/2;
        mergeSort(nums,left,mid);
        mergeSort(nums,mid+1,right);
        int cur1=left,cur2=mid+1,k=0;
        while(cur1<=mid && cur2<=right) {
            if(nums[cur1]<=nums[cur2]) {
                tmpNums[k]=nums[cur2];
                tmpIndex[k++]=index[cur2++];
            } else {
                ret[index[cur1]]+=(right-cur2+1);
                tmpNums[k]=nums[cur1];
                tmpIndex[k++]=index[cur1++];
            }
        }
        while(cur1<=mid) {
            tmpNums[k]=nums[cur1];
            tmpIndex[k++]=index[cur1++];
        }
        while(cur2<=right) {
            tmpNums[k]=nums[cur2];
            tmpIndex[k++]=index[cur2++];
        }
        for(int j=left;j<=right;j++) {
            nums[j]=tmpNums[j-left];
            index[j]=tmpIndex[j-left];
        }
    }
}
